# operator==,!=,<,<=,>,>=(std::experimental::observer_ptr)

From cppreference.com
< cpp‎ | experimental‎ | observer ptr

template< class W1, class W2 > bool operator==( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (1) | (library fundamentals TS v2)
template< class W1, class W2 > bool operator!=( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (2) | (library fundamentals TS v2)
template< class W > bool operator==( const observer_ptr<W>& p, std::nullptr_t ) noexcept; | (3) | (library fundamentals TS v2)
template< class W > bool operator==( std::nullptr_t, const observer_ptr<W>& p ) noexcept; | (4) | (library fundamentals TS v2)
template< class W > bool operator!=( const observer_ptr<W>& p, std::nullptr_t ) noexcept; | (5) | (library fundamentals TS v2)
template< class W > bool operator!=( std::nullptr_t, const observer_ptr<W>& p ) noexcept; | (6) | (library fundamentals TS v2)
template< class W1, class W2 > bool operator<( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (7) | (library fundamentals TS v2)
template< class W1, class W2 > bool operator>( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (8) | (library fundamentals TS v2)
template< class W1, class W2 > bool operator<=( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (9) | (library fundamentals TS v2)
template< class W1, class W2 > bool operator>=( const observer_ptr<W1>& p1, const observer_ptr<W2>& p2 ); | (10) | (library fundamentals TS v2)

Compares the pointer values of two `observer_ptr`s, or an `observer_ptr` and nullptr.

1,2) Equality comparison for two `observer_ptr`s.
3-6) Equality comparison for an `observer_ptr` and nullptr.
7-10) Ordered comparison for two `observer_ptr`s.

### Parameters

p, p1, p2 | - | `observer_ptr`s to compare

### Return value

1) p1.get() == p2.get()
2) !(p1 == p2)
3,4) !p
5,6) (bool)p
7) std::less<W3>()(p1.get(), p2.get()), where `W3` is the composite pointer type of `W1*` and `W2*`.
8) p2 < p1
9) !(p2 < p1)
10) !(p1 < p2)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/experimental/observer_ptr/operator_cmp&oldid=157742"